fsck: add support for whole-disk locking (-l option)

This feature allows to call multiple independent fsck instances rather
than use only one "fsck -A" process.

The lock uses LOCK_EX flock(2). The lock request is ignored if the
whole-disk is non-rotating disk. The verbose mode (-V) provides
information about disk locking.

Note that "fsck -l" does not care if the device is stacked, for
example if you want to call "fsck -l /dev/md0" and "fsck -l /dev/md1"
then the underlying devices will not be locked. The traditional "fsck
-A" does not run in parallel for stacked devices.

Requested-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fsck/fsck.h b/fsck/fsck.h
index d212622f1..5612b218a 100644
--- a/fsck/fsck.h
+++ b/fsck/fsck.h
@@ -58,6 +58,7 @@ struct fs_info {
 struct fsck_instance {
 	int	pid;
 	int	flags;
+	int	lock;		/* flock()ed whole disk file descriptor or -1 */
 	int	exit_status;
 	time_t	start_time;
 	char *	prog;